(1) Field of the Invention
The present invention relates to a transferring apparatus for transferring a thin substrate such as a wafer, a glass substrate or the like, and further to a transferring apparatus having an articulated robot constructed so as to reduce the swivel radius.
(2) Description of the Prior Art
In general, a thin substrate, such as a silicon wafer, a glass substrate or the like, is processed and transferred within a clean room. Therefore also a transferring apparatus for transferring a thin substrate is installed within a clean room, and has an arm body to be swiveled in the horizontal direction so that the thin substrate is transferred from the prescribed position to the position for the substrate to be processed. In the prior art, a transfer robot arranged within the transferring apparatus has a hand supporting the thin substrate and a drive unit which rotates the hand or moves it up and down, and the drive unit is arranged within a machine bed. A transfer robot 110 shown in FIG. 16 is known well usually, and has a machine bed 111, an arm body 112 which is rotated or moved up and down with respect to the bed 11 and is flexional, and a hand 113 which is rotatable with respect to the arm body 112 at the top end of the arm body 112. The arm body 112 is constituted by two arms, a first arm 114 which is rotated with respect to the machine bed 111 by a motor (not shown) arranged within the machine bed 111, and a second arm 115 which is adjacent at the top end of the first arm 114. The first arm 114 and the second arm 115 are driven and transmitted by a pulley belt (not shown), and by the driving and transmission, the second arm 115 is rotated with respect to the first arm 114. The robot 110 having the arm body 112 and the hand 113 attracts a thin substrate housed within a cassette (not shown) and is moved linearly, thereby the thin substrate can be taken out or taken in without contacting with both ends of the cassette.
In the transfer robot in the prior art, however, since the hand is moved linearly by the flexion of the two arms, the moving area of the hand is limited. Therefore when there are many processings of the work or when the work is moved to a remote distance in one process, a rail is installed below the robot and the robot itself is moved along the rail. However, when the robot itself is moved, a space for the transferring apparatus itself becomes large and the installation cost is increased. In order to solve the problems, such improvement has been tried that the number of arms is increased and a motor is mounted to a part of respective swivel units and an articulated robot raising the degree of freedom of the moving trajectory of the arm is arranged thereby the transfer stroke of the substrate is lengthened and the moving of the robot itself is eliminated.
However, when the moving of the hand is performed by simply increasing the number of arms and the horizontal swivel is performed, the swivel radius becomes large and the distance between the robot and the cassette within the transferring apparatus or the distance between the processing stage must be set large thereby the apparatus becomes large scale.